//
//  Stack.cpp
//  模拟实现栈
//
//  Created by Yan Zihao on 2024/10/19.
//
#include"Stack.h"

// 初始化和销毁
void STInit(ST* pst)
{
    assert(pst);

    pst->a = NULL;
    // top指向栈顶数据的下一个位置
    pst->top = 0;

    // top指向栈顶数据
    //pst->top = -1;

    pst->capacity = 0;
}

void STDestroy(ST* pst)
{
    assert(pst);

    free(pst->a);
    pst->a = NULL;
    pst->top = pst->capacity = 0;
}

// 入栈  出栈
void STPush(ST* pst, STDataType x)
{
    assert(pst);

    // 扩容
    if (pst->top == pst->capacity)
    {
        int newcapacity = pst->capacity == 0 ? 4 : pst->capacity * 2;
        STDataType* tmp = (STDataType*)realloc(pst->a, newcapacity * sizeof(STDataType));
        if (tmp == NULL)
        {
            perror("realloc fail");
            return;
        }

        pst->a = tmp;
        pst->capacity = newcapacity;
    }

    pst->a[pst->top] = x;
    pst->top++;
}

void STPop(ST* pst)
{
    assert(pst);
    assert(pst->top > 0);

    pst->top--;
}

// 取栈顶数据
STDataType STTop(ST* pst)
{
    assert(pst);
    assert(pst->top > 0);

    return pst->a[pst->top - 1];
}

// 判空
bool STEmpty(ST* pst)
{
    assert(pst);

    return pst->top == 0;
}

// 获取数据个数
int STSize(ST* pst)
{
    assert(pst);

    return pst->top;
}

#include"Stack.h"

int main()
{
    ST s;
    STInit(&s);
    STPush(&s, 1);
    STPush(&s, 2);
    STPush(&s, 3);
    STPush(&s, 4);

    printf("%d\n", STTop(&s));
    STPop(&s);
    printf("%d\n", STTop(&s));
    STPop(&s);

    printf("%d\n", STTop(&s));

    STDestroy(&s);

    return 0;
}
